Metal sprayer for use in vacuum or inert atmosphere



Oct. 14, 1958 R. E. MONROE 2,356,237

METAL SPRAYER FOR USE IN VACUUM OR INERT ATMOSPHERE Filed March 31. 1955 5 Sheets-Sheet 1 R. E. MONROE Oct. 14, 1958 METAL SPRAYER FOR USE IN VACUUM 0R INERT ATMOSPHERE Filed March 31. 1955 5 Sheets-Sheet 2;

Oct. 14, 1958 R. E. MONROE 2,856,237

METAL SPRAYER FOR USE IN VACUUM OR INERT ATMOSPHERE Filed March 31. 1955 3 Sheets-Sh t 3 F153 ll a 1:15 K?" I coming from the nozzle 12.

Unite States Patent METAL SPRAYER FOR UsE IN VACUUM on INERT ATMOSPHERE Robert E. Monroe, Columbus, Ohio, assignor to the United States of America as represented by the United States Atomic Energy Commission Application March 31, 1955, Serial No. 498,455

4 Claims. (Cl. 299-28.6)

This invention relates to a spraying apparatus and, more particularly, to an apparatus by which wire is melted by an electric arc and sprayed by a gas stream against an object so as to coat the same.

When uranium is to be coated with zirconium by spraying, it is necessary that the spraying apparatus operate in an inert atmosphere and without the use of an oxidizing flame for melting the metal to be sprayed. The present invention concerns an apparatus that melts a metal wire for spraying by means of an electric arc and is capable of operation in an inert atmosphere and with the use of a high-velocity stream of an inert gas. The apparatus is also capable of being used in an ordinary oxygen-containing atmosphere.

According to the present invention, two straight tubes that may be angularly adjusted with respect to one another guide wires toward a region where an electric arc is created between the wires and melts them so that a high-velocity stream of gas directed at the region may transform the melted portions of the wires into a spray. Variation in the spraying is achieved by adjustment of the angle between the wires as they come together, which adjustment is carried out by adjustment of the angle between the straight tubes that guide the wires.

In the drawings:

Fig. 1 is a plan View of the novel apparatus of the present invention;

Fig. 2 is a side view of the apparatus;

Fig. 3 is a vertical sectional view taken on the line 3-3 of Fig. l and showing how certain feed rolls of the apparatus are mounted and driven;

Fig. 4 is a vertical sectional view taken on the line 4--4 of Fig. 1 and illustrating the parts of the apparatus for feeding and guiding a wire; and

Fig. 5 is a horizontal sectional view taken on the line 55 of Fig. 2 and illustrating the mounting of an upper feed roll.

With reference to Fig. l, the novel apparatus of the present invention includes two straight tubes 10, which during operation are arranged at an angle toone another, instead of being parallel as shown, so that metal wires 11 emerging from the tubes meet in alignment with a gas nozzle 12 and beyond the end thereof. The tubes and the wires 11 emerging therefrom form part of an .electric circuit so that an arc is formed at the contacting portions of the wires and produces melted metal that is transformed into a spray by a high-velocity stream of gas Adjustment of the angle at which the wires 11 meet and adjustment of the end of :the nozzle 12 with respect to the are created between the wires will affect the shape of the spray. Adjustment of the angle between the wires 11 is produced by adjust- :ment of the angle between the tubes 10, which adjustment is carried out by adjustment of feeding mechanisms 13 of which the tubes 10 form part about pivot axes 14 with respect to a table 15 upon which the feeding mechanisms "are mounted. Adjustment of the end of the nozzle 12 with respect to the are between the wires 11 is achieved Patented Oct. 14, 1958 by the aforesaid adjustment of the angle between the tubes 11 and also by longitudinal adjustment of the nozzle 12.

As shown in Fig. 2, the table 15 comprises a top 16 upon which the feeding mechanisms 13 are directly mounted, four legs 17, and four caster wheels 18 attached to the lower ends of the legs so as to enable the table 15 to be wheeled about.

Each feeding mechanism 13 comprises a horizontal plate 19 lying flat upon the table top 16 and a vertical plate 20 secured to one side of the horizontal plate 19, an upper feed roll 21, and a lower feed roll 22. Rolls 21 and 22 are formed of a suitable hard insulating material and are grooved to accommodate the wires 11. The plates 19 and 20 are secured to one another by screws 23 which are shown in Fig. 2. The two sets of plates 19 and 20 are arranged with respect to one another so that the outer sides of the vertical plates 20 face one another and the horizontal plates 19 extend in opposite directions from the regions at which they are secured to the vertical plates 20. When as shown in Fig. l, the wireguiding tubes 10 are parallel to one another, the vertical plates 20 are also parallel, but when in operation the tubes 10 are angled toward one another to allow the wires 11 emerging therefrom to come into contact, the vertical plates 20 are similarly angled to one another. Each vertical plate 20 carries a needle bearing 24 by means of which a shaft 25 for the lower feeding roll 22 is journaled. Each vertical plate 20 has a recess or opening 26 and a portion 27 having thickness less than that of the rest of the vertical plate, which recess and reduced portion accommodate a bearingblock 28 which carries a needle bearing 29 journaling a shaft 30 for the upper feed roll 21. As shown in Fig. 5, the bearing block 28 has a bifurcated portion that straddles the reduced portion 27 of the vertical plate 20 and is pivotally connected thereto by a pin 31 which is secured in the reduced portion 27 by a set screw 32. A pressure screw 33 which is threaded through the upper end of the vertical plate 20 is engageable at its end with a recess in the bearing block 28 so that by suitable angular adjustment of the screw 33 the bearing block 28 may be pressed downward so as to press the upper feed roll 21 more firmly against the lower feed roll 22.

The feed rolls 21 and 22 are secured to the shafts 25 and 30, respectively, for rotation therewith by means of nuts 34 threaded on the shafts 25 and 3t) and washers 35 positioned on the shafts at opposite sides of the rolls 21 and 22. Each of the rolls 21 and 22 is clamped by the nut 34 against the needle bearing 24 or 29 which is in turn clamped against a shoulder 36 formed on the shaft 25 or 30. The shafts 25 and 30 are drivingly interconnected by means of spur gears 37 which are pinned to the shafts and mesh with one another. The shaft 25 is longer than the shaft 30 so as to accommodate a bevei gear 38 which is pinned to the shaft 25 just beyond the spur gear 37.

On the right-hand feeding mechanism 13 as viewed in Fig. 3, the bevel gear 38 meshes with a bevel gear 39 positioned therebelow and pinned to a short. vertical shaft 4% which lies on the pivot axis 14. The shaft 40 is journaled in the horizontal plate 19 by means of a thrust hearing 41 and in the table top 16 by means of a ball bearing 42. On the left-hand feeding mechanism 13 as viewed in Fig. 3, the bevel gear 38 meshes with a bevel gear 43 which lies above it and is pinned to a long vertical shaft 44 which lies on the pivot axis 14. The upper end of the shaft 44 is journaled in a thrust bearing 45 which is carried in the horizontal bearing plate 46 secured by screws 47 to the upper end of the vertical plate 20. A collar 48 is secure-d to the shaft 44 in engagement with the lower side of the thrust bearing 45. The lower portion of the shaft 44 is journaled in ball bearings 49 and 50 carried, respectively, in the horizontal plate 19 and the table top 16. To the lower ends of the shafts 4t) and 44 spur gears 51 are secured, and a thrust washer 51a is mounted on each of the shafts 46 and 44 between the spur gear 51 and the pulley bearing 42 or 50 in the table top 1.6. A spur gear 52 which lies between the spur gears 51 meshes with them and is carried and driven by a motor 53 which is supported from the under-side of the table top 16 by means of a bracket 54. The motor 53, acting through the gears 51 and 52, the vertical shafts 4i) and 44', the bevel gears 38, 39, and 43, and the roll shafts 25 and 3d, drives the two sets of upper and lower feed rolls 21 and 22. The right-hand feeding mechanism has a short vertical shaft 40 and the bevel gear 39 below the bevel gear 38 with which it meshes, whereas the left-hand feeding mechanism 13 has the long vertical shaft 44 and the bevel gear 43 above the bevel gear 38 withwhich it meshes, so that both sets of feeding rolls 21 and 22 will feed the wires 11 in the same direction.

The rolls 21 and 22 feed the wires 11 through the tubes 10. Each of these tubes is made of copper and is secured in a copper ring 55 to one end of a copper bar 56, to the opposite end of which is connected a lead 56a coming from a soure of electric power. Each copper bar 56 extends horizontally and is clamped between an outer insulating plate 57 and an inner insulating plate 58, which are vertical and extend transversely to the vertical plate 21). The inner insulating plate 58 is secured to a vertical insulating post 59 by means of bolts 60 and nuts 61, which, as shown in Fig. 4, are set in recesses in the post 59. The post 59 is secured at one end of the vertical plate 20 on its outer side facing the other vertical plate 20 to the other post 59 by means of screws 62. The outer insulating plate 20 and the copper bar 56 are secured to the inner insulating plate 58 by means of bolts 63.

As shown in Fig. 2, the gas nozzle 12 is connected by means of a fitting 64 to a pipe 65 which is adjustably carried in a bracket 66 which is secured to one end of the table top 16 by means of screws 67 and extends therebeyond. Lengthwise adjustment of the gas nozzle 12 is accomplished by shifting of the pipe 65 in the bracket 66, and a set screw 68 fixes the pipe 65 to nozzle 12 in any desired position.

The wires 11 come to the feed rolls 21 and 2.2 from insulating reels 69 upon which they are wound. For each feeding mechanism 13 the reel 69 is carried upon an arm 70 which is secured to one end of the horizontal plate 19 and extends horizontally therefrom along and beyond the table top 16 in general parallelism with the vertical plate 20. The reel 69 is carried upon the arm 75 by means of a plate 71 which is located between the lower end of the reel and the arm 7%) and by a shaft 72 which extends through the arm 70 to the reel so as to permit the reel to rotate as the wire 11 is unwound therefrom. A spring 73 which is mounted on the shaft 72 acts between the upper end of the reel 69 and a collar 74 secured to the upper end of the shaft 72 to urge the reel against the plate 71 and the plate in turn against the arm 76, whereby sufficient friction is created between the plate 71 and the arm 75} to prevent the reel from rotating freely as the wire is pulled therefrom by the feed rolls 21 and 22. The end of the wire wound upon the reel 69 may be secured thereto as indicated at 75, by being inserted through the upper end of the reel and bent over.

On each feeding mechanism 13 the wire 11 is guided from the reel 69 to the feeding rolls 21 and 22 by means of tubular guide 76 through which the wire passes. Tubular guide '76 extends through and is grasped by a flexible rubber piece 77 which is secured by screws 78 to the vertical plate at the end thereof opposite that at which the insulating post 59 is secured. An external collar 79 is secured to the tubular guide 76 and serves by engagement with the rubber piece 77 to prevent the'wire 11 from pulling the tubular guide into the rolls 21 and 22. The ends of the tubular guide 76 are near or at the feeding rolls 21 and 22 and the reel 69. The rubber piece 77, mounting the tubular guide 76, has suflicient flexibility to permit the tubular guide to move up and down along the reel 69 to accommodate the wire 11 as it is being unwound from the reel. The end of the tubular guide 76 at or near the reels 21' and 22 is relatively close to the rubber piece 77, and the end of the tubular guide at the reel is relatively far from the piece 77, so that the swinging movement of the tubular guide 76 that occurs with unreeling of the wire 11 is at a minimum at the rolls 21 and 22 and at a maximum at the reel 69.

The feeding mechanisms 13 may be pivoted about their axes 14 when the angle between the wire-guiding devices is to be changed. The drive of the feeding rolls 21 and 22 is not disturbed by pivoting of the feeding mechanism, since the drive shafts 40 and 44 for the feed rolls have their axes co-incident with the pivot axes 14. The feeding mechanisms 13 may be fixed in desired angular positions by means of screws 80 which, as shown in Fig. 3, have heads engaging the underside of the table top 16 and threaded shanks that engage the plates 19 and 20. The screws 80 go through arcuate slots 81 in the table top 16, which slots provide room for the screws 80 in the various angular positions of the feed mechanisms 13.

In operation of the apparatus of the present invention, two wires 11 are fed at the same speed by the two sets of rolls 21 and 22, because the two spur gears 51 are the same size, and the bevel gears 39 and 43 are the same size. In actual operation, the tubes 11 are not parallel as shown in Fig. 1, but are angled toward one another so that the portions of the wires 11 coming out of the'tubes 141 meet at a region that is aligned with the gas nozzle 12 and located beyond its end. The portions of the wires 11 coming into contact form an electric arc, because they complete an electric circuit with a source of electric power which circuit includes the wires 11, the tubes 10, the rings 55, the conductor bars 56, and the leads 56a. The high-velocity stream of gas coming from the nozzle 12 transforms the portions of the wires 11 melting in the are into a spray that is carried against an object (not shown) to be coated.

The apparatus of the present invention is ideally suited for spraying zirconium upon uranium, because it operates well in a neutral atmosphere. By neutral is meant a gas which is non-reactive with the metal which is to be sprayed. In this case the apparatus is placed in a gastight enclosure to which a vacuum is applied for removal of air and into which a neutral gas such as argon is introduced. Argon under pressure is also supplied by the nozzle 12' so as to impinge upon the molten portions of zirconium wires as they come together and form an arc. Either direct current or alternating current may be used to produce the arc. The shape of the spray of molten metal may be changed by adjustments of the angle between the wire-guiding device 10 and adjustments of'the spacing between the end of the nozzle 12 and the are formed between the wires 11.

The apparatus of the present invention is also adapted to spray stainless'steel upon iron or steel. In this case the apparatus may be operated in the open air, since it is unnecessary to use a neutral atmosphere.

It will be appreciated that the portions of the wires 11 back of the conductor bars 56 on the device 10 are insulated, because the parts through which the wires move either are insulated or are formed of insulating material. The plates 57, the posts 59, and the feed rolls 21 and 22 are formed of insulating material. The tubular guides 76 are formed of copper, but are insulated, being mounted in the rubber pieces 77. The reels 69 are formed of insulating material.

The intention is to limit the invention only within the scope of the appended claims.

I claim: v

1. An apparatus for spraying metal comprising a wheeled table; a pair of opposed mechanisms mounted thereon for feeding metal wires, each feeding mechanism comprising a horizontal plate lying flat upon and slidable on the table top, a vertical plate secured to and extending upward from one end of the horizontal plate, the vertical plates generally facing one another on their outer sides and the horizontal plates extending in opposite directions from their regions secured to the vertical plates, each feeding mechanism further comprising a pair of upper and lower feed rolls positioned on the outer side ofthe vertical plate, upper and lower drive shafts for the upper and lower feed rolls geared to one another, means journaling the lower drive shaft directly in the vertical plate, a hearing block journaling the upper feed roll, means pivotally mounting the bearing block in the vertical plate, a pressure screw threaded through the vertical plate and engaging the bearing block so as to set the pressure of the upper feed roll against the lower feed roll, a straight horizontal conducting wire-guiding tube extending from adjacent the feed rolls, and means securing the tube to the vertical plate and insulating the tube from the vertical plate, the other parts of the feeding mechanisms, and the table; a gas-supplying nozzle mounted on the table so as to extend between the tubes; means pivotally mounting the feeding mechanisms on the table so as to enable the tubes to be adjusted with respect to one another and with respect to the nozzle, whereby wires coming from the feed rolls through the tubes may come into contact with one another at various angles and in line with the gas coming from the nozzle; means connecting a source of electric power with the tubes whereby an electric circuit is completed with the source through the tubes and the portions of the wires emerging from the tubes into contact with one another, and an electric arc is created at such contact of the wires, resulting in melting thereof and spraying of the melted metal by the gas coming from the pipe; and means connecting a source of mechanical power with one drive shaft for the feed rolls of each feeding mechanism and including a shaft having its axis coincident with the pivot axis of the feeding mechanism.

2. The apparatus specified in claim 1; the mounting of the gas nozzle on the table providing for lengthwise adjustment of the pipe to accommodate shifting of the con- 6 tact between the wires coming from the tubes as the angle between the tubes is adjusted; the means securing each tube to the associated vertical plate comprising a vertical insulating post secured to the vertical plate at one edge thereof, a pair of insulating plates extending vertically and transversely to the vertical plate, a horizontal conducting bar clamped between the plates and secured at one end to the tube to support the same, means securing one insulating plate to the insulating post, and means securing the other insulating plate and the conducting bar to the said one insulating plate, the source of electric power being connected with the tube through the conducting bar.

3. The apparatus specified in claim 2, each feeding mechanism further comprising an arm secured to the horizontal plate and extending horizontally therefrom in general parallelism to the vertical plate, a reel mounted on the end of the arm remote from the horizontal plate for storing a supply of the wire fed through the rolls and the tube, a shaft carrying the reel and connected at its lower end to the arm, a collar attached to the upper end of the arm, and a spring acting between the collar and the reel to cause the wire on the reel and from the reel to the rolls to remain taut.

4. The apparatus specified in claim 3, each feeding mechanism further comprising a flexible piece secured to the vertical plate, a tubular guide mounted in and extending through the piece so as to accommodate the wire on its way from the reel to the rolls, the flexibility of the piece permitting the guide to swing along the reel to facilitate unreeling of the wire from the reel, the flexible piece being relatively near to a first end of the guide at the rolls and relatively far from a second end of the guide at the reel to minimize the swinging of the first end and to maximize the swinging of the second end, the tubular guide having an external collar engageable with the flexible piece on the side away from the rolls for preventing the wire from taking the guide into the rolls.

Schoop Mar. 30, 1915 Muller Jan. 12, 1926 

